International Travel Advice

Basics

Traveling abroad can increase your exposure to infectious diseases. Your risk for acquiring an infectious disease is particularly high if you are traveling to an underdeveloped country that may not have modern water or sewage systems, or if you are going into an area where outbreaks of infectious diseases are known to occur.

People traveling in underdeveloped tropical and subtropical countries are especially at risk for developing an illness. Studies show that 50% to 75% of travelers in these regions develop some type of health problem. Most of these problems are minor, however, with only about 5% requiring medical attention, and fewer than 1% requiring hospitalization.

The most significant infectious health hazards for Americans traveling abroad are traveler's diarrhea, malaria, hepatitis A, and typhoid fever. While the Centers for Disease Control and Prevention list 43 infectious diseases of concern to travelers, it is important to remember that infectious illnesses are responsible for only about 1% of deaths among American travelers. Most Americans who die while abroad succumb to heart disease (49%) or injuries (22%).

Causes

Travel-related infectious diseases are caused by viruses, bacteria, or parasites. Some infectious diseases can be transmitted by breathing tiny contaminated droplets from a sneeze or cough, or by touching an infected surface and then touching your nose, eyes, or mouth. Other diseases can be transmitted through sexual contact. Eating food or drinking water contaminated with a germ (pathogen) can also make a traveler ill. Sometimes an insect such as a mosquito, fly, or tick can act as a carrier for pathogens, and can transmit disease with a bite.

Most cases of traveler's diarrhea are caused by bacteria.
Escherichia coliis the bacterium that most commonly causes traveler's diarrhea, but viruses and parasites can also trigger the illness. Traveler's diarrhea is most commonly contracted by ingesting contaminated food or drink.

Though this is the same bacteria that has caused severe food outbreaks in the U.S. in recent years, it may be a milder strain, and is unlikely to cause life-threatening diarrhea.

Malaria is caused by amoeba-like parasites that live and multiply within red blood cells. Four species of malaria parasites can infect humans and cause malaria—Plasmodium falciparum,P. malariae, P. vivax,and P. ovale. Malaria caused by P. falciparum is the most serious form; it can lead to life-threatening complications, including kidney failure and coma. Malaria parasites are injected into humans by the Anopheles mosquito, often at dusk when the insects are feeding.

The hepatitis A virus causes hepatitis A. Hepatitis A is transmitted when a person puts something in his or her mouth that has been contaminated with stool from someone infected with the virus. Travelers who contract hepatitis A often do so by eating or drinking under poor hygienic conditions.

Typhoid fever is caused by the bacterium Salmonella typhi. Like hepatitis A, typhoid fever is usually acquired by ingesting fecal-contaminated food and water. Once S. typhi bacteria are ingested, they multiply and spread into the bloodstream.

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